Mecha-con!
you were a bit distracted werent you? :b it says right above the image "This post is #75 in the Mecha-con! CG pool "
http://www.anime-sharing.com/forum/hentai-games-38/japanese-%5B110408%5D-%5Bonomatope*%5D-%E3%82%81%E3%81%A1%E3%82%83%E5%A9%9A%EF%BC%81mecha-con-54567/